# Passphrase-file paramater in mender client

**URL:** <https://hub.mender.io/t/passphrase-file-paramater-in-mender-client/6274>\
**Category:** General Discussions\
**Created:** [October 18, 2023, 7:55am UTC](https://hub.mender.io/t/passphrase-file-paramater-in-mender-client/6274 "2023-10-18T07:55:56Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![edmundwatson](https://yyz2.discourse-cdn.com/flex036/user_avatar/hub.mender.io/edmundwatson/32/2039_2.png) [@edmundwatson](https://hub.mender.io/u/edmundwatson)\
**Post date:** [October 18, 2023, 7:55am UTC](https://hub.mender.io/t/passphrase-file-paramater-in-mender-client/6274/1 "2023-10-18T07:55:56Z")

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Hello,

I was trying to look for documenation on mender client.  
i.e mender --passphrase-file passkey.file  
I know it has a options --passphrase-file

–passphrase-file value Passphrase file for decrypting an encrypted private key. ‘-’ loads passphrase from stdin.

What is the private key used for?

Thanks  
Ed